...子查询可以在 SELECT、INSERT、UPDATE 或 DELETE 语句中使用,通常用于实现复杂的查询条件、过滤、聚合等操作。1...子查询的类型A. 单行子查询(Scalar Subquery)单行子查询返回一个单一的值(一个行一个列)。它可以用于在查询条件中进行比较。...多行子查询(Multiple Rows Subquery)多行子查询返回多个值,通常...
CREATETABLEstudents(idINTAUTO_INCREMENTPRIMARYKEY,nameVARCHAR(100),ageINT,majorVARCHAR(100)); 1. 2. 3. 4. 5. 6. 现在,我们希望插入多条学生信息。我们可以使用以下INSERT语句: INSERTINTOstudents(name,age,major)VALUES('Alice',20,'Computer Science'),('Bob',22,'Mathematics'),('Charlie',21,'Ph...
drop table if exists t_vip; create table t_vip( id int, name varchar(255) unique, email varchar(255) ); insert into t_vip(id,name,email) values(1,'zhangsan','zhangsan@123.com'); insert into t_vip(id,name,email) values(2,'lisi','lisi@123.com'); insert into t_vip(id,name,...
1)I need to insert b(known value) into table1 and database to create id(because of PK autoincrement). 2)I need to insert multiple rows into table2 using the created id (step 1) and c (known values). Do I need transactions to ensure insertion (in case of system crash ) in both...
MySQL INSERT – insert multiple rows# In order to insert multiple rows into a table, you use the INSERT statement with the following syntax: 1 2 3 4 INSERT INTO table(column1,column2...) VALUES (value1,value2,...), (value1,value2,...), ...; In this form, the value list of...
Intention shared (IS): Transaction T intends to set S locks on individual rows in table t. Intention exclusive (IX): Transaction T intends to set X locks on those rows. 事务在请求S锁和X锁前,需要先获得对应的IS、IX锁。 Before atransactioncan acquire an S lockona rowintablet, ...
记录了0+0的写出0字节(0B)已复制,0.000219914秒,0.0kB/秒[root@localhosttmp]# ll -h 20m.img-rw-r--r-- 1 root root 20M 6月 6 15:15 20m.imgmysql>createtablet1(idintauto_incrementprimarykey,alongblob);Query OK,0rowsaffected(0.03sec)mysql>insertintot1values(NULL,load_file('/tmp/20m.img...
rowsDO--构建批量插入语句SET@insert_sql='INSERT INTO batch_insert_test (fileid_1, fileid_2, fileid_3, fileid_4, fileid_5, fileid_6, fileid_7, fileid_8, fileid_9, fileid_10) VALUES ';--生成当前批次的1000条数据SET@batch_values='';SET@j=0;WHILE@j<batch_countANDi<total_rows...
CREATE TABLE t8 ( a int AUTO_INCREMENT PRIMARY KEY, b int, c int, unique key ub(b) ) engine=InnoDB; insert into t8 values (NULL,1,2) 2.3 过程分析 在每次执行一条语句之后都执行show innodb engine status查看事务的状态,执行完 delete 语句,事务相关日志显示如下: ...
I am trying to insert a large number of rows into a mysql 5.5 database but it is very slow. Same code on POSTGRES and ORACLE is 100s times faster. For mysql I construct my INSERT statements as follows: INSERT INTO MY_TABLE VALUES ( 1, 1, 'text' ) , ( 2, 1, 'some text')...